JPS6216503B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to preventing active materials from falling off in paste type lead-acid batteries.

The electrode plates of paste-type lead-acid batteries are made by filling an active material holding base with paste-type lead powder and allowing it to mature and solidify. However, as the positive electrode active material is repeatedly charged and discharged, it becomes fine and falls off, reducing the capacity. The disadvantage was that internal short circuits occurred as the temperature decreased.

In order to prevent the positive electrode plate active material from falling off, glass fibers are formed into a mat shape using a water-soluble or insoluble binder, and the glass fibers are attached to the positive electrode side of the separator to hold the finely divided active material that has fallen off. has traditionally been practiced. However, this method requires that the glass mat and the positive electrode plate be brought into close contact with each other, so a method has been used in which ribs are provided on the partition wall of the battery case to apply pressure to the electrode plate group. The disadvantage was that a large amount of force was required to insert the electrode plate group into the battery case, impairing workability.

An object of the present invention is to eliminate the above-mentioned drawbacks and prevent the positive electrode plate active material from falling off without impairing the workability of inserting the electrode plate group.

The present invention has been made to achieve the above object, and by using an elastic sheet compressed in the thickness direction and solidified with a water-soluble binder as a separator, after assembling a lead-acid battery, When the liquid is injected, the water-soluble binder is dissolved and the sheet's own elasticity pressurizes the electrode plate group, which prevents the positive electrode active material from falling off and eliminates the need for pressurization during battery assembly. This improves work efficiency. This sheet is porous in order to have conductivity as a separator and to hold the finely separated positive electrode active material without falling off along the surface, and it also has a porous structure that allows the separated positive electrode active material to penetrate through the sheet. In order to prevent this, it is desirable that the surface in contact with the negative electrode plate have only micropores, and it is more desirable that the diameter of the pores be 10 microns or less. Generally, the finest lead powder for paste used in lead-acid batteries has a diameter of 1 micron or more, but since several particles aggregate in liquid, it is unlikely that a short circuit will occur through pores of 10 microns or less. Conceivable.

An embodiment of the present invention will be described.

An elastic porous sheet compressed in the thickness direction by bolting from both sides with a porous pressure plate was immersed in an impregnating tank filled with a water-soluble binder solution and pulled up. Thereafter, this material is heated with a heater to vaporize the solvent of the solution and solidify the water-soluble binder. By removing the pressure plates attached to both sides of the porous sheet, the porous elastic sheet solidified body 3
is obtained.

Next, the porous sheet solidified body 3 is sandwiched between the negative electrode plate 1 and the positive electrode plate 2 as a separator to assemble the electrode plate group, and this is stored in a battery case. The body 3 has a thin layer 4 having micropores on one side thereof, and is arranged such that the thin layer 4 having micropores is in contact with the negative electrode plate 1. The partition wall 5 of the battery case does not need to be provided with ribs, and there is no need to arrange a protective plate in contact with the outermost cathode plate 1 of the electrode plate group. The thickness of the first electrode plate group is smaller than the width of the cell 6, but by adding the electrolyte, the water-soluble binder is eluted from the solidified porous elastic sheet 3, and the thickness of the porous elastic sheet 3' increases. is thicker than the porous elastic sheet solidified body 3, so the thickness of the entire electrode plate group is larger than the width of the cell 6, and due to the elasticity of the porous elastic sheet 3', the negative electrode plate 1 and the positive electrode plate 2 are Pressurized to prevent active material from falling off.

In order to form a thin layer 4 having only micropores on the porous elastic sheet solidified body 3, a water-insoluble polymer solution may be applied to the surface of the porous elastic sheet solidified body 3 and then dried.

As described above, according to the present invention, the solidified porous elastic sheet is in a state where the thickness is compressed by the water-soluble binder. The workability of inserting the electrode group into the battery case, which had been impaired due to the Therefore, there is no need to provide ribs on the partition wall of the battery case, making molding easier when manufacturing the battery case, and since the partition wall is flat, there is no need for a protective plate. The industrial value is enormous, as it makes it possible to make lead-acid batteries smaller and lighter by removing the free electrolyte that existed between the ribs.

[Brief explanation of the drawing]

The drawing is a sectional view of a main part showing the manufacturing state of a lead-acid battery according to an embodiment of the present invention. 1 is a cathode plate, 2 is an anode plate, 3 is a solidified porous elastic sheet, 3' is a porous elastic sheet, 4 is a thin layer having micropores, 5 is a partition wall, and 6 is a cell.

Claims (1)

[Claims] 1. An elastic porous sheet compressed in the thickness direction is impregnated with a solution of a water-soluble binder, then dried and solidified, and remains compressed even after external pressure is removed. A method for manufacturing a lead-acid battery, which comprises assembling a lead-acid battery using a separator as described above, and then injecting an electrolyte. 2. The porous sheet described in claim 1 is characterized in that one side of the porous sheet is a thin layer having only micropores, and the remaining portion has relatively large pores. manufacturing method for lead-acid batteries. 3. The method for manufacturing a lead-acid battery according to claim 2, characterized in that a thin layer having micropores with a diameter of 10 microns or less is formed on one side of the porous sheet. 4. The thin layer having only micropores is formed by applying a water-insoluble polymer solution to the surface of a porous sheet and then drying it. Manufacturing method for lead-acid batteries.